In the game of ice hockey, a goal is used which typically measures about 72 inches across, about 48 inches high, and about 37 inches deep. Vertical goal posts rise from the forward side corners, and the lower rear outline of the goal is generally defined by two curves having spaced-apart centres of curvature. The two curves generally define a kidney shape when seen in plan.
In simpler hockey facilities, a hockey goal is merely positioned on the ice, and maintains its position due to its weight. However, any substantial impact from a player will often move the hockey goal. When that happens, the game must be suspended, and the hockey goal put back into a position which is marked in colour under the ice surface.
Other installations have a removable stub post sticking upwardly out of the ice at the positions of the forward side goal posts, and the goal posts are hollow with open bottom ends, so that they can fit over the stub posts. When the ice is to be used for activities other than hockey games, the goal is removed, and the stub posts are removed from the ice.
The use of these stub posts registering within the forward side goal posts produces a hockey goal which is very firmly anchored in position. When a hockey player collides with the goal during play, the full force of the impact is absorbed by the player's body, and this often results in broken or dislocated shoulders and other damage. It is well understood that, if the hockey goal were retained in place by some means which allowed a sufficient impact to dislodge the goal from position, then the hockey player's body would not be required to absorb as much of the energy of impact, and injuries could be reduced.